1. Field of the Invention
This invention relates to novel compositions for the softening and/or loosening of unwanted organic coatings for removal from surfaces, such as oven surfaces which are soiled by baked-on organic or carbon deposits. This invention also relates to methods of making these novel compositions and to methods of using them. Other unwanted organic coatings which can be softened or loosened for removal by the compositions of this invention include organic paint, varnish, shellac or lacquer coatings that are desired to be stripped from surfaces to which they are applied.
2. Description of the Prior Art
The job of periodically cleaning soil from interior surfaces of home ovens or commercial food ovens or cooking utensils often is disagreeable. The soil normally has been baked-on by several heatings between the time it was deposited and the time that its removal is attempted and, therefore, is difficult to remove. Mechanical removal as by chipping with a tool or scrubbing with abrasives is arduous, potentially hazardous to the surface and/or the worker and usually is not very effective. Two currently popular means for removing soils of this type are (a) the self-cleaning oven which uses extremely high temperatures and catalytic oven surfaces to oxidize and burn off the soil and (b) the application of a cleaner which dissolves, softens and/or lifts the soil from the surfaces. Most of the oven cleaners currently being marketed contain strong caustic or alkaline materials which can cause severe burns and tissue damage if they contact the skin or eyes and there is a high level of interest in safer oven cleaning compositions.
As illustrated by U.S. Pat. Nos. 3,031,408; 3,031,409; 3,079,284; 3,196,046; 3,331,943; 3,335,092; 3,549,419; 3,684,576; 3,715,324; 3,779,933; 3,829,387 and others, oven interiors soiled by baked-on grease and spattered foods have been cleaned by applying solutions of saponification agents or materials that provide ammonia gas which condenses on the oven walls, usually preceded or followed by heating of the soiled interiors in order to cause a chemical reaction with the soil. However, the use of these solutions is accompanied by certain drawbacks, such as, harsh fumes emanating from the oven, and/or they are harmful to the eyes and skin on contact due to caustic. These solutions are also capable of producing corrosive damage to aluminum surfaces, if accidentally spilled on them.
Products containing catalytic metal salts and oxides are also described which substitute for catalytic coatings in self-cleaning ovens. These coatings require higher than normal cooking temperatures in order to be operable.
U.S. Pat. No. 3,658,711 discloses oven cleaning compositions containing an alkali metal or ammonium carbonate, phosphate, borate or silicate and a polyoxyethylene glycol amine enhancer. While these compositions avoid the use of caustic alkalis, the amine contributes to a higher pH and presents the possibility of injury to the skin or tissue. Alkali metal carbonates are themselves quite stable and will not convert to alkali metal hydroxides under the conditions of oridinary use and, thus, are lacking in cleaning ability.
U.S. Pat. No. 3,808,051 describes oven cleaning compositions containing salts of mixed alkali metals and a volatile weak organic acid. The salt mixtures become molten at elevated temperatures and the weak organic acid moiety volatilizes to release alkali metal ions which attack the soil. Thereafter, the soil residue is washed from the surface. These compositions require relatively high temperatures to become operable and cannot function at room temperature. Furthermore, during washing to remove the soil, the user is faced with the potential hazards of removing and handling caustic alkalis.